ELECTROCHEMICAL-BEHAVIOR OF 1024-MILD-STEEL IN SLIGHTLY ALKALINE BICARBONATE SOLUTIONS

The electrochemical behaviour of 1024 mild steel electrodes is investi gated in the presence of 0.05-0.5 M sodium bicarbonate in aqueous solu tion at pH 8.9 and 25 degrees C. Voltammograms are obtained with a rot ating gold ring-mild steel electrode and the effect of the NaHCO3 conc entration, the potential limits and the rotation speed of the disc ele ctrode is considered. The voltammograms display an oxidation peak curr ent at low potentials, a passivity region and a transpassive region at high potentials for the potential sweep in the anodic direction. The oxidation current in the passivity region is practically independent o f the applied potential and the NaHCO3 concentration. The rate-determi ning step of the oxidation reaction in both the oxidation peak current region and the transpassive region is determined.